If your gels are chemically crosslinked, you can try to put them in a solution with strong ionic strength such as a concentrated NaCl solution which should destroy the complex to some extent.

For chemically cross-linked hydrogels, you can use also HCl 0.1 M or HNO3 0.1 M, one or two times. After that, you should regenerate the gel with NaOH 0.1 M, washing then to neutral pH. Thus, you have the gel prepared for the next cycle of sorption.